• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.189-196
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• 2001

Objective : We tested the hypothesis that photodynamic therapy(PDT) with Photofrin inhibits tumor invasion of U87 human glioma cells using several in vitro assay to measure tumor invasiveness. The effects of PDT on cell growth, directional migration and cell invasion were investigated. Material and Method : Tumor cells were treated with Photofrin at various doses and at a fixed optical(632nm) dose of $100mJ/cm^2$. Cytotoxicity was tested using the MTT method. Invasion assays including the matrigelartificial basement membrane barrier migration and spheroid confrontation with confocal microscopic analysis were used to study the relationship between PDT and invasiveness. Result : U87 cells showed a dose dependent cytotoxic response to increasing Photofrin dose. Data from the matrigel artificial basement membrane assay indicate that PDT inhibits the U87 cell migration dose dependently. Low doses of subcytotoxic PDT treatment, such as 2.5ug/ml Photofrin dose, also appeared to significantly inhibit migration of U87 cells(p<0.05). In co-cultures between U87 cell spheroids and brain aggregates, progressive invasion with destruction of the brain aggregate occurs. The extent of tumor cell infiltration and proportion or intact brain aggregate remaining after 24h differs in Photofrin PDT treated versus Photofrin only control, with changes suggestive of a dose-response effect. Conclusion : our data indicate that PDT with Photofrin significantly inhibits the invasiveness of U87 cells, and this inhibition is dose dependent.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.321-335
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• 2021

Particulate matter (PM10 and PM2.5 with a diameter less than 10 and 2.5 ㎛, respectively) can be absorbed by the human body and adversely affect human health. Although most of the PM monitoring are based on ground-based observations, they are limited to point-based measurement sites, which leads to uncertainty in PM estimation for regions without observation sites. It is possible to overcome their spatial limitation by using satellite data. In this study, we developed machine learning-based retrieval algorithm for ground-level PM10 and PM2.5 concentrations using aerosol parameters from Geostationary Ocean Color Imager (GOCI) satellite and various meteorological parameters from a numerical weather prediction model during January to December of 2019. Gradient Boosted Regression Trees (GBRT) and Light Gradient Boosting Machine (LightGBM) were used to estimate PM concentrations. The model performances were examined for two types of feature sets-all input parameters (Feature set 1) and a subset of input parameters without meteorological and land-cover parameters (Feature set 2). Both models showed higher accuracy (about 10 % higher in R2) by using the Feature set 1 than the Feature set 2. The GBRT model using Feature set 1 was chosen as the final model for further analysis(PM10: R2 = 0.82, nRMSE = 34.9 %, PM2.5: R2 = 0.75, nRMSE = 35.6 %). The spatial distribution of the seasonal and annual-averaged PM concentrations was similar with in-situ observations, except for the northeastern part of China with bright surface reflectance. Their spatial distribution and seasonal changes were well matched with in-situ measurements.

• Journal of the Korean earth science society
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• v.42 no.3
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• pp.278-295
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• 2021

China's shutdown due to COVID-19 in 2020 reduced air pollutant emissions, which is located on the windward side of South Korea. The positive temperature anomaly and negative zonal wind anomaly from northern Mongolia to South Korea through eastern China presented warm and stationary air masses during January and February 2020. Decreased concentrations of PM10, NO₂, and O₃ were measured at Seokmo-ri and Pado-ri, located in the central-western region of South Korea, due to decreased emissions in China from January to March 2020. After China's shutdown from January to March 2020, in Pado-ri, the ratio of monthly average concentrations in that period with those of PM10 and O₃ in the last four years decreased by approximately 0.7-4.7% and 9.2-22.8%, respectively. In January 2020, during the Lunar New Year holidays in China, concentrations of PM10, NO₂, and O₃ at Seokmo-ri and Pado-ri decreased just as much as it did during the same period in the last four years. However, average concentrations in January 2020 decreased before and after the Lunar New Year holidays in China when compared with those in January of the last four years. In Seokmori, ratios of actual and predicted values (${\bar{O}_s$/M) for PM10, NO₂, and O₃ concentrations were calculated as 70.8 to 89.7%, 70.5 to 87.1%, and 72.5 to 97.1%, respectively, during January and March 2020. Moreover, those of Pado-ri were 79.6 to 93.5%, 67.7 to 84.9%, and 83.7 to 94.6%, respectively. In January 2020, the aerosol optical depth (AOD) data showed a higher distribution than that of the last four years due to photochemical reactions in regions from northern Mongolia to eastern China and the Korean Peninsula. However, the decrease in AOD values compared with those of the last four years was attributed to the decrease in emissions of precursors that generate secondary aerosols in China during March 2020.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.460-471
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• 2019

The aim of this study was to examine the scale and market share of Chinese's research facility & equipment in the domestic research equipment market of basic and analytical science field for analyzing the difference of the number and amount of construction by year of acquisition, national research facility equipment standard classification code, and type of institution based on the information of the research equipment invested by the Korean government for the past 14 years. In addition, we analyzed the correlation among the year of acquisition, equipment standard classification code, and type of institution variables. As of January 1 2019, from 2005 to 2018, 50 Chinese's research facilities & equipments (main equipment with a construction cost of 30 million won or more) built in the basic and analytical science fields were selected for this study and their number of construction, amount of construction, year of acquisition, type of institution, and standard classification code were analyzed. Differences of the number and amount of construction with-in and by year of acquisition, standard classification code, and type of institution were tested using a single sample Chi-square test, Mann-Whitney U test, and Kruskal-wallis test. The correlation among the three variables was analyzed by using the Chi-square test of cross-tabulation analysis. And there was a statistically significant correlation among the year of acquisition, standard classification code, and type of institution (p<.05). Compared to the 2000s, in the 2010s, high-priced Optical Electronics/Video Equipment was installed at private universities, private enterprises, and government-affiliated research institute. Therefore, the domestic construction status of Chinese's research facility & equipment in the basic science and analytical science field is less than that of the domestic ones, but the number and the amount of construction are increasing statistically. So it is necessary for the government to be able to recognize the possibility that the Chinese's research facility and equipment can encroach on the domestic research industry market and to prepare related provision.

• Korean Journal of Heritage: History & Science
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• v.45 no.1
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• pp.122-147
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• 2012

The Four-guardian statues in Song-gwang buddhist temple, Suncheon, Korea, have been remade in AD 1628 and have been repaired and repainted over several times since then. Therefore, the study of the pigments applied on the statues can provide good chance for investigation about pigments used in the late Chosun Period. Pigments on fragments from Gwang-mok(Virupaksha), one of the Four-guardian statues, have been analyzed by optical microscope, SEM-EDX and XRD in order to identify the components and compounds. Six types of materials were found from the fragments, which are soil layer with brown clay band, soil layer containing a lot of fibers, Korean paper with loose texture, Korean paper with dense texture, silk, and hemp textile. Presumably, the soil layer which have brown clay band is basis layer and the other layers are repaired layers. From comparative study for the components of the pigments, applied on upper and lower parts of the repaired layers, we have concluded that those repaired layers had been applied on the statue by the following order; basis layer ${\rightarrow}$ Korean paper with loose texture ${\rightarrow}$ soil containing a lot of fibers ${\rightarrow}$ silk ${\rightarrow}$ hemp textile and Korean paper with dense texture. In addition, the years that those materials were applied on the statue have been estimated as 1720~1891, 1926, 1946 and 1976, respectively. The distinct features of each age are as the following; lead white and copper chloride hydroxide are major white and green pigments before 1891, zinc white, barium white, emerald green, and ultramarine blue appear after 1926 and titanium white uprises around 1976. Our result presented here, study on pigments applied on traditional statues over several different periods, will provide good database for future study on pigments used for traditional painting in Buddist temples and Dancheong.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.233-245
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• 2021

Many studies on the microstructures in rocks have been conducted using experimental methods with various equipment as well as natural rock studies to see the development of microstructures and understand their mechanisms. Grain boundary migration of mineral aggregates in rocks could cause grain growth or grain size changes during metamorphism or deformation as one of the main recrystallization mechanisms. This study suggests improved ways regarding the analog material experiments with reformed equipment to see sequential observations of these grain boundary migration. It can be more efficient than the existing techniques and carry out an appropriate microstructure analysis. This reformed equipment was implemented to enable optical manipulation by mounting polarizing plates capable of rotating operation on a stereoscopic microscope and a deformation rig capable of experimenting with analog materials. The equipment can automatically control the temperature and strain rate of the deformation rig by microcontrollers and programming and can take digital photomicrographs with constant time intervals during the experiment to observe any microstructure changes. The composite images synthesized using images by rotated polarizing plates enable us to see more accurate grain boundaries. As a rock analog material, norcamphor(C7H10O) was used, which has similar birefringence to quartz. Static grain growth and simple shear deformation experiments were performed using the norcamphor to verify the effectiveness of the equipment. The static grain growth experiments showed the characteristics of typical grain growth behavior. The number of grains decreases and the average grain size increases over time. These case experiments also showed a clear difference between the growth curves with three temperature conditions. The result of the simple shear deformation experiment under the medium temperature-low strain rate showed no significant change in the average grain size but presented the increased elongation of grain shapes in the direction of about 53° regarding the direction perpendicular to the shearing direction as the shear strain increases over time. These microstructures are interpreted as both the plastic deformation and the internal recovery process in grains are balanced by the deformation under the given experimental conditions. These experiments using the reformed equipment represent the ability to sequentially observe changing the microstructure during experiments as desired in the tests with the analog material during the entire process.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.109-116
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• 2021

Purpose: The purpose of this study is to evaluate the usefulness of Surface-Guided Patient Setup by comparing the patient positioning accuracy when image-guided radiation therapy was used for Markerless patients(unmarked on the skin) using Surface-Guided Patient Setup and Marker patients(marked on the skin) using Laser-Based Patient Setup. Materials And Methods: The position error during IGRT was compared between a Markerless patient initially set up with SGPS using an optical surface scanning system using three cameras and a Marker patient initially set up with LBPS that aligns the laser with the marker drawn on the patient's skin. Both SGPS and LBPS were performed on 20 prostate cancer patients and 10 Stereotactic Radiation Surgery patients, respectively, and SGPS was performed on an additional 60 breast cancer patients. All were performed IGRT using CBCT or OBI. Position error of 6 degrees of freedom was obtained using Auto-Matching System, and comparison and analysis were performed using Offline-Review in the treatment planning system. Result: The difference between the root mean square (RMS) of SGPS and LBPS in prostate cancer patients was Vrt -0.02cm, Log -0.02cm, Lat 0.01cm, Pit -0.01°, Rol -0.01°, Rtn -0.01°, SRS patients was Vrt 0.02cm, Log -0.05cm, Lat 0.00cm, Pit -0.30°, Rol -0.15°, Rtn -0.33°. there was no significant difference between the two regions. According to the IGRT standard of breast cancer patients, RMS was Vrt 0.26, Log 0.21, Lat 0.15, Pit 0.81, Rol 0.49, Rtn 0.59. Conclusion:. As a result of this study, the position error value of SGPS compared to LBPS did not show a significant difference between prostate cancer patients and SRS patients. In the case of additionally performed SGPS breast cancer patients, the position error value was not large based on IGRT. Therefore, it is considered that it will be useful to replace LBPS with SGPS, which has the great advantage of not requiring patient skin marking..

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.1
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• pp.55-64
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• 2022

The potassium cream soap with fatty acid called cleaning foam has a crystal gel structure, and unlike an emulsion system, it is weak to shear stress and shows characteristics that are easily separated under high temperature storage conditions. The crystal gel structure of cleansing foams is significantly influenced by the nature and proportion of fatty acids, degree of neutralization, and the nature and proportion of polyols. In order to investigate the effect of these parameters on the crystal gel structure, a ternary system consisting of water/KOH/fatty acid was investigated in this study. The investigation of differential scanning calorimeter (DSC) revealed that the eutectic point was found at the ratio of myristic acid (MA) : stearic acid (SA) = 3 : 1 and ternary systems were the most stable at the eutectic point. However, the increase in fatty acid content had little effect on stability. On the basis of viscosity and polarized optical microscopy (POM) measurements, the optimum degree of neutralization was found to be about 75%. The system was stable when the melting point (T_m) of the ternary system was higher than the storage temperature and the crystal phase was transferred to lamellar gel phase, but the increase in fatty acid content had little effect on stability. The addition of polyols to the ternary system played an important role in changing the T_m and causing phase transition. The structure of the cleansing foams were confirmed through cryogenic scanning electron microscope (Cryo-SEM), small and wide angle X-ray scattering (SAXS and WAXS) analysis. Since butylene glycol (BG), propylene glycol (PG), and dipropylene glycol (DPG) lowered the T_m and hindered the lamellar gel formation, they were unsuitable for the formation of stable cleansing foam. In contrast, glycerin, PEG-400, and sorbitol increased the T_m, and facilitated the formation of lamellar gel phase, which led to a stable ternary system. Glycerin was found to be the most optimal agent to prepare a cleansing foam with enhanced stability.

• Journal of Korean Elementary Science Education
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• v.41 no.2
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• pp.283-294
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• 2022

Although the concept of light is important in the elementary school curriculum, substantial research suggests that students and teachers have difficulties in understanding it. Therefore, it is necessary to analyze the reasons for these difficulties-whether it is due to the content or due to the presentation method of contents, structure, and expression. The national curriculum and textbooks of Korea, the US, China, and Japan were comparatively analyzed from the following perspectives: 1) key concepts of light, 2) structure of light units in the textbook, 3) materials, light sources, and optics used in light units. Consequently, there were differences between countries in their inclusion of the concept of light in the curriculum. In particular, the Korean curriculum studies the concept of refraction by a convex lens, whereas the concept of light, light source, and vision is not introduced. Furthermore, countries also differed in their structuring of units. The Korean curriculum was presented segmentally by concept rather than structured according to core ideas or perspectives, and the connection between concepts was unclear. In addition, there were differences between the countries in materials, light sources, and optical instruments to explain key concepts. On using light, the US curriculum provides a purpose and uses light to achieve it, and China and Korea understand the concept. It was divided into the method of using the material to deepen. Based on the results of this analysis, the implications for the elementary science curriculum in Korea were derived as follows. First, it is necessary to introduce concepts sequentially and organize them so that the connection between concepts is well expressed. Second, it is necessary to introduce light and light sources as the predominant concepts. Third, it is necessary to include the principle of seeing objects. Fourth, it is necessary to adjust the material and content level of the refraction concept included in the light and lens unit. Fifth, an integrated approach is required because light has a deep connection with various concepts included in the elementary science curriculum.

• Journal of Korea Foundry Society
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• v.42 no.6
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• pp.337-346
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• 2022

In order to optimize the solution treatment conditions of Al-7Si-(0.3~0.5)Mg-(0~0.5)Cu alloys, a series of heat treatment experiments were conducted under various solution treatment times up to 7 hours at 545℃, followed by a microstructural analysis using optical microscopy, FE-SEM, and Brinell hardness measurements. Rapid coarsening of eutectic Si particles was observed in the alloys during the first 3 hours of solution treatment but the size of those Si particles did not change at longer solution treatment conditions. Meanwhile, the degree of spheroidisation of eutectic Si particles increased until the solution treatment time was increased up to 7 hours. Q-Al5Cu2Mg8Si6 andθ-Al2Cu were observed in as-cast Cu-containing Al alloys but the intermetallic compounds were dissolved completely after 3 hours of solution treatment at 545℃. Depending on the initial Mg composition of the Al alloys, π-Al8FeMg3Si either disappeared in the alloy with 0.3wt% of Mg content after 5 hours of solution treatment or remained in the alloy with 0.5wt% of Mg content after 7 hours of solution treatment time. Mg and Cu content in the primary-α phase of the Al alloys increased until the solution treatment time reached 5 hours, which was in accordance with the dissolution behavior of Mg or Cu-containing intermetallic compounds with respect to the solution treatment time. From the results of microstructural changes in the Al-7Si-Mg-Cu alloys during solution treatment, it was concluded that at least 5 hours of solution treatment at 545℃ is required to maximize the age hardening effect of the present Al alloys. The same optimal solution treatment conditions could also be derived from Brinell hardness values of the present Al-7Si-Mg-Cu alloys measured at different solution treatment conditions.